Lower back pain is the most common musculoskeletal disorder of industrialized society and the most common cause of disability in persons younger than 45 years. Given that 90% of adults experience lower back pain sometime in their life, this is the most costly of all medical diagnoses when time off from work, long-term disability, and medical and legal expenses are taken into account.
The lumbosacral facet joint is believed to be the source of pain in 15-40% of patients with chronic lower back pain and it is well known that facet pain is the etiology for most cases of mechanical lower back pain. The facet joints (posterior zygo-apophyseal joints) are diarthrodial joints with a synovial lining, the surfaces of which are covered with hyaline cartilage, which is susceptible to arthritic changes and arthropathies. Like any synovial joint, degeneration, inflammation, and injury can lead to pain with joint motion, causing restriction of motion secondary to pain, and thus deconditioning.
The articular cartilaginous surfaces found within the facet joint can degenerate due to mechanical or biological factors and cause pain as with other joint osteoarthritis. For example, a patient may suffer from arthritic facet joints, severe facet joint tropism or otherwise deformed facet joints, facet joint injuries, etc. There is currently a lack of suitable intervention procedures for facet joint disorders. Facet blocks with anesthetic and cortisone, facet denervation procedures, radiofrequency ablation of the nerve supply to the joint, or even spinal fusions have been recommended. In the early stages of degeneration, pain may be controlled by blocking the medial branch of the lumbar facet joints providing temporary relief of pain.
Percutaneous radiofrequency neurotomy is a method of denaturing the nerves that innervate the facet joint through coagulation, thus conferring temporary relief of pain. Once the axons regenerate, pain often returns. The therapeutic benefit of this procedure remains controversial.
Facetectomy, or the removal of the facet joints, may provide some relief, but significantly decreases the stiffness of the spinal column (i.e., hypermobility) in all planes of motion: flexion and extension, lateral bending, and rotation. Furthermore, problems with the facet joints can also complicate treatments associated with other portions of the spine.
Intra-articular facet joint injection with corticosteroids and a local anesthetic is one of the interventional procedures performed. The long-term benefit of intra-articular injection remains controversial. Accordingly, there is a need for a facet joint treatment that addresses these concerns.
U.S. Pat. No. 6,648,918 to McKay et.al., discloses fusion implants for promoting bone growth in intervertebral disc space. Collagen soaked Bone Morphogenic Proteins (BMP's) is disclosed as a carrier in the implanted device.
U.S. Pat. No. 5,769,899 to Schwartz et.al., discloses a bio-absorbable cartilage repair system for regenerating damaged or destroyed cartilage using hyaluronic acid.
US Patent Application 2005-00025765 to DiMauro et.al., discloses administration of therapeutic inhibitors specific to the pro-inflammatory molecules to inflamed joints. Preferably growth factors such as BMP's were delivered after the inhibition of the pro-inflammatory molecules had taken effect. Accordingly, Dimauro does not teach a procedure involving directly administering a therapeutic agent to obtain a biological repair effect.
US Patent Application 2004-0228901 to Frieu et.al., discloses injection of collagen to a synovial joint including a facet joint. US Patent Application 2004-059418 to McKay et.al., discloses treating degenerating synovial joints and facet joints.
Given the above, it is desirable to have a lasting treatment for facet pain rather than providing temporary relief.